High Temperature Graphite Research Articles

High temperature oxidation of carbon by atomic oxygen

The true kinetics of the attack of high temperature graphite by both atomic and diatomic oxygen have been studied using microwave discharge-fast flow system techniques. In the surface temperature range 1100°K–2000°K the oxidation probability for O-atom attack 1. (i) exceeds that for O 2, by factors between 5 and as much as 80, 2. (ii) passes through a maximum in this temperature range, as does the O 2 attack probability on the same surface, and 3. (iii) is independent of oxygen partial pressure (corresponding to a first order reaction), in contrast to the kinetic order of the O 2/carbon reaction. Several mechanistic implications of these results are briefly discussed.

A high temperature (3000 C) graphite furnace for laboratory use

The construction is described of a high temperature (3000°C) graphite resistance furnace incorporating two new features. These are the use of a graphite guard-tube to facilitate easy replacement or renewal of the element and the use of carbon felt and carbon wool as a thermal insulator in place of carbon black. The assembly is simple to operate and can be constructed easily and relatively inexpensively.

High-temperature dilatometer for measuring shrinkage during sintering

The laboratory device for studying the dilatometric effect, made of high-temperature graphite, is reliable in operation and makes possible the measurement of temperatures up to 2500°C with a sufficiently high accuracy (an error of only 2.6%).

Graphite-metal compatibility at elevated temperatures

Numerous metals and alloys were screened for application as a cladding material on graphite to operate in helium at temperatures up to 1010° C. It was found that the heat-resistant nickel-base alloys, the stainless steels, and molybdenum all carburized rapidly above 816° C. In the case of niobium, a reactive metal, the results emphasize the importance of maintaining high purity helium to prevent embrittlement. Of the alloys tested, nickel-copper alloys appeared to be the most promising for use as a hightemperature graphite cladding. Aging data indicated that Monel is more resistant to graphitization than nickel.